The typical drive system for used propelling a marine vessel has an engine or motor, a transmission, and an associated drive shaft assembly. The drive shaft assembly will have a drive shaft housing encasing a rotating drive shaft configured with the engine transmission and a rotatable propeller assembly and will have associated bearing assemblies. The drive shaft housing typically extends outwardly from the stem of the vessel with the propeller assembly and at least a portion of the drive housing positioned below the bottom of the vessel.
In many marine drive systems the drive shaft housing will extend downward below the bottom of the vessel at a position that is perpendicular, or approaching perpendicular, to the water surface depending upon the upward or downward adjustment or trim of the drive housing employed during operation of the vessel. When the drive shaft housing and propeller assembly extend below the bottom of the vessel, both are completely exposed to waterway obstructions such as tree stumps, underwater humps, reefs, floating or underwater debris particularly when the vessel is traversing a waterway.
When the vessel is propelled in shallow waterways, such as marshes or swamps, waterway obstructions such as floating and underwater vegetation, tree limbs, branches, roots, mud bottoms, rocks, and reefs are likely to be encountered. If a waterway obstruction is encountered, the components of the marine drive system may be severely damaged. A damaged drive shaft or propeller assembly will cause the vessel to lose propulsion and may create an inability to steer or further operate the vessel, all providing a potential safety hazard and risk of harm to the vessel operator, any passengers, and other vessels in the vicinity. Repairing the resulting damage to these assemblies may be time consuming and expensive.
Consequently, there is a need for an improved drive system for marine vessels that will minimize or eliminate the risk of drive system damage caused by waterway obstructions.